The present invention relates to guide arrangements for portable power saws and made up of a guide plate adapted to be placed on the work and a stand plate fixed to the saw. The guide plate possesses a raised rail running in the feed direction of the saw. In use, the saw with the stand plate is placed on the guide plate so that the stand plate fits round the rail and the stand plate may then be moved along the guide plate on the rail, the guiding section straddling the rail and guiding the stand plate on the rail. This means that the saw is guided in the length direction parallel to the rail of the guide plate and it is possible for straight cuts to be sawn with a high degree of accuracy without any danger of the saw running askew.
A guide arrangement as designed on these lines may for example have a piece of metal section functioning as the rail and the stand plate may be designed to mate therewith so that there is positive engagement between the stand plate and the rail. The cross section of the rail may more specially be generally rectangular so that it may take the form of a square section pipe produced by extrusion. In this case, the stand plate will have a matching socket into which the rail fits. To take one example, the stand plate may be fitted with two sliding shoes mounted on the rail like a straddling saddle having the opposite form thereto. Furthermore, it is possible for the stand plate to be stamped so as to have a guiding means in the form of a pressed lip, and in a more specially simple design the guide means on the guide plate takes the form of a slot, whose upwardly bent edges rest against the rail.
With the rail and the saddle or runner designed to fit on the stand plate there are necessarily some inaccuracies in manufacture. In order to take care of such inaccuracies a relatively large play is left between the stand plate and the rail in known designs. In the case of a rail in the form of an extruded section, the inaccuracies due to manufacture are in a range of .+-.0.15 mm and a stand plate formed by bending is likely to be subject to even greater inaccuracies so that ultimately the amount of play in the guide will be anything up to 0.4 mm. However, such a large amount of play has a serious effect on the accuracy of cutting with the saw. Although it is naturally possible in principle to produce guide means with a more accurate guiding effect by machining the parts, then the extra expense and work involved are hard to justify economically.